Selector-circuit for automatic and semi-automatic telephone systems.



l C. L. GOODRUM. SELECTOR cmcun FORAUTGMAUC AND SEMI-AUTOMATIC TELEPHONE SYSTEMS.

APPLICATION FILED APR. 27 I916.

Patented July 30, 1918.

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UNITED STATES PATENT OFFICE.

CHARLES L. GOODRUM, OENEXV YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, 015 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SELECTOR-CIRCUIT FOR AUTOMATIC AND SEMI-AUTOMATIC TELEPHONEQSYSTEMS.

Specification of Letters Patent. Patented July 30, 1918.

Application filed April 27, 1916. Serial No. 93,869. I

To all whom it may concern:

Be it known that I, CHARLES L. GooDRUM, a citizen of the United States, residing at- New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Selector- Circuits for Automatic and Semi-Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to a selector circuit for automatic and semi-automatic telephone systems.

The purpose of this invention is to prevent the sending of false impulses through careless removal of the receiver from its hook.

The invention is herein applied to an automatic telephone system of the character disclosed in applicants co-pending application, Serial No. 41,587, filed July 23, 1915. Only so much of the circuit arrangements are shown in the present application as are necessary to a clear understanding of this invention.

The mechanism diagrammatically indicated within the dotted line in the drawing is individual to a subscribers line, and represents a line switch of the general character disclosed in Patent No. 1,151,543, of August 24, 1915, to A. E. Keith. To the right of the dotted rectangle, there is diagrammatically indicated a first selector switch, such as disclosed in applicants ap plication Serial No. 41,587, filed July 23, 1915, and circuits therefor having the present invention embodied therein.

The side switch indicated in the drawing may be similar in structure to that shown in Patent No. 815,176 of March 13, 1906, to A. E. Keith and J. and C. J. Erickson, but differs therefrom in that in certain instances the wipers are moved upon the energization instead of upon the deenergization of the controlling magnet. A side switch of this character is disclosed in the patent of O. F. Forsberg, No, 1,252,420, issued January 8, 1918.

It is believed that the invention will now be clearly understood by tracing the operation of setting up a connection through the selector switch shown in the drawing.

Assuming that the subscriber, whose substation apparatus is indicated at the left in the drawing, removes his receiver from the hook, a circuit will be completed from battery through the left-hand winding of line. relay 1, left-hand armature and contact of cut-off relay 2, over the line and through the substation apparatus, back over the lower "side of the line, through the righthand armature and back contact of cut-off relay 2, and through the right-hand winding of relay 1, back to battery. Relay 1 pulls up and completes a circuit from grounded battery through the right-hand winding of the plunger operating magnet 3, armature and front contact of relay 1 to ground. This magnet is energized and causes the operation of the plunger or contact operating device 4, by means of which the line spring terminals 19 and 20 are forced into engagement with the trunk terminals adjacent thereto.

In accordance with the well-known operation of a switch of this character, it will be understood that the plunger at the time of its operation was associated with a contact set in which an idle trunk terminated. Upon the closure of the line and trunk contacts, a circuit is completed from grounded battery through the left-hand winding of the plunger operating magnet 3, cut-off relay 2, the lower line switch spring 20, trunk terminal, relay 5 and back contact and armature of release magnet 6 to ground. Magnet 3 is maintained energized and relays 2 and 5 attract their armatures. Cutoif relay 2 clears the line to the first selector. Relay 5 at its inner armature grounds the trunk contact at the master switch, thus causing the idle plungers to move to a position before the next idle trunk in a manner clearly explained in Patent No. 1,151,543, of August 24, 1915, to A. E, Keith. v

Simultaneously with the above,a circuit is completed from grounded battery through stepping relay 7, side switch wiper 17, first position, upper contacts of the line switch, front contact and left-hand armature of relay 2, over the subscribers line and through the substation circuit, and back over the other side of the line, right-hand armature and front contact of relay 2, lower switch spring 20, trunk contact and relay 5, back contact and armature of magnet 6, to

ground. This interrupts the circuit for the release magnet 6 which would otherwise be established from grounded battery, relay 6',

gize. The slow energization of relay 8 116- 'cessitates that the calling circuit be closed for a definite period of time before an energizing circuit for rotary magnet 10 will be completed. This period will be sufliciently long to allowthe calling party to complete the removal of his receiver from the hook. This provision prevents the sending of false impulses by oscillation of the switchhook through careless removal of the receiver.

The energization of slow release relay 8 completes a shunt circuit around the resistance 18 from grounded battery through relay 8, outermost left-hand armature and front Contact of relay 8, front contact and armature of relay 7, back contact and armature of relay 9 to ground. The shuntingot resistance 18 permits more current to flow through relay 8, causing full saturation of the core. lVhen the current-flow through relay 8, which is provided with a copper sleeve, is interrupted, the magnetism dies down slowly, causin slow release.

. The subscriber now works his sending device to interrupt the circuit of relay 7.

'lVitlrthe first deenergization of relay 7, the

rotary stepping magnet 10 and the slow-release relay 11 are energized in parallel by a circuit from grounded battery through said relay and magnet, with its controlling side switch wiper 21 in first position, in parallel, front contact of relay 8, back contact of relay 7 and back contact of relay 9 to ground. Relays 8 and 11 being slow to release, remain energized throughout the series of impulses. The energization of slow-release relay 11 completes a circuit for escape magnet 12 from grounded battery, magnet 12, front contact and left-hand armature of relay 11 to ground. Each interruption of the line circuit and consequent deenergization of stepping relay 7 causes the rotary magnet 10 to move the switch brushes to select a group of trunks.

Upon the termination of the impulses, re.- lay 7 remains energized, thus holding open the circuit of relay 11, which falls off and opens the previously established circuit for the escape magnet 12, thus causing the side switch wipers to move to second position.

In the second position 0]": the side switch, a circuit is established from grounded battery through the vertical stepping magnet 13, the individual interrupter 22 of said magnet, side switch wiper 14, front contact and armature of'relay 7, and back contact and armature of test relay 9 to ground. The terminals of busy trunks traversed by the lower switch brush will be provided with raised potential so the test relay 9 will not be energized. l/Vhen, however, the switch brush engagcsthe terminal of an idle trunk, which will be connected to earth, relay 9 will pull up, breaking the circuit for the stepping magnet 13 and completing a circuit from grounded battery through escape magnet 12, front contact and right-hand armature of slow rclease relay '8 which is maintained energized through the hunting opera tion, and front contact and armature of relay 9 to ground. The escape magnet is energized and moves the side switch wipers to position 3 in a manner which is clearly disclosed in the applicants application, Serial No. 872,743, filed November 18, 1914:.

As the operation of the switches succeeding the first selector may be of substantially the same character as that shown in applicants Patent No. 1,251,503, issued January 1, 1918, the operationof establishing the rest of the connection will-not be described. In the first and second positions of the side switch wipers, all deenergizations of stepping relay 7 are-momentary only, and therefore, relay 8 remains energized. This maintains open the circuit from battery through release magnet 6, olf-normal contact 1'5 and side switch wiper 16, which would otherwise be completed through the back contact and armature of relay 8, back contact and armature of relay 7, back contact and armature of relay 9. It the calling subscriber should interrupt his substation circuit while the series of impulses were being sent, stepping relay 7 would fall 05, causing the deenergization of relay 8 and the completion of the release circuit just described.

At the time the side switch moves out of position 2 and the stepping relay 7 becomes deeuergized, relay 9 is energized, but when the side switch reaches position 3, relay 9 becomes de'energized, due to certain changes at the succeeding selector switch, thus opening up the release circuit which would otherwise be established from grounded battery throughmagnet 6, contact 15, wiper 16, back contact and right-hand armature of relay 8, front contact and armature of relay 9 to ground. At the termination of the conversation, relay 9 becomes energized due to circuit changes at the succeeding switch in a manner which will be well understood from the above mentioned Patent No. 1,251,503.

Should the subscriber, after the operation of his line switch, replace his receiver on the hook without operating his sending device, the stepping relay 7 will become deenergized and a circuit will be completed from grounded battery through the release magnet, the outermost left-hand armature and front contact of relay 5 and wiper 16 to ground, through the back contacts and armatures of relays 8, 7 and 9 as before.

The operation of magnet 6 interrupts the circuit of relays 5 and 2 and magnet 3, and if the switch has moved from normal, magnet 6 establishes a holding circuit for itself which is maintained through the off-normal contact- 15, until the switch reaches normal position.

The deenergization of magnet 3 alloWs the plunger 1 tobe retracted. The armatures of relay 2 fall off and connect the subsoribers line to his line relay 1, and the re traction of the armatures of relay 5 removes the busy potential from the trunk contact at the master controller, thus permitting the trunk to again be selected.

What is claimed is:

1. In a telephone exchange system, telephone lines, automatic switching means for completing connection between said lines, means for selecting said automatic switching means, an impulse sending device for directively controlling the movement of said automatic switching means, and means for preventing any actuation of said automatic switching means for a predetermined interval after the mentioned switching means has been selected for use.

2. In a telephone exchange system, telephone lines, automatic switching means for completing connection between said lines, means for selecting said automatic switching means, an impulse sending device for directively controlling the movement of said automatic switching means, electromagnetic means for actuating said automatic switching means, and means for preventing any energization of said electromagnetic means for a predetermined interval after the mentioned switching means has been selected for use.

3. In a telephone system, telephone lines, means including an automatic switch for connecting said lines, a stepping magnet, an impulse sending device, a stepping relay for said stepping magnet, responsive to impulses from said impulse sending device, a control relay cooperating with said stepping relay to operatively control said stepping magnet, a resistance coil, and an energizing circuit for said control relay established by the operation of said stepping relay andincluding said resistance coil for rendering said control relay slow to energize.

4. In a telephone system, telephone lines, means including an automatic switch for connecting said lines, a stepping magnet, an impulse sending device, a stepping relay for said stepping magnet, responsive to impulses from said impulse sending device, a control relay cooperating with said stepping relay to operatively control said stepping magnet, a resistance coil normally in series with the winding of said control relay, and a shunt circuit about said resistance coil completed on the energization of said control relay thereby rendering said control relay slow to deenergize.

5. In a telephone exchange system, telephone lines, automatic switching means for completing connection between said lines, means for selecting said automatic switching means, a combination of fast and slow. relays for controlling. the actuation of said automatic switching means, and means associated with certain of said relays for preventing any actuation of said automatic switching means for a predetermined interval after the said switching means has been selected for use. i

6. In an automatic telephone system, groups of telephone lines, automatic switching means for completing a connection between lines of each of said groups, means for selecting said automatic switching means, a combination of fast and slow relays for controlling the actuation of said automatic switching means, and a resistance inserted in the circuit of one of said relays to prevent the actuation of said switching means for a predetermined interval after the said switching means has been selected for use,

7. In an automatic telephone system, incoming and outgoing groups of lines, automatic switching means for completing the connection between desired lines of each of said groups, a combination of fast and slow relays, means ointly controlled by said relays for selectively actuating said automatic switching means, a resistance inserted in the circuit of one of the relays of said combination to render it slow to energize, and a shunt circuit about said resistance completed on the energization of said relay.

8. A circuit including a switch, an operating magnet for selectively operating said switch, a pair of relays for jointly controlling said magnet, a resistance in the circuit of one of said relays, and a shunt circuit completed about said resistance on its energization.

In witness whereof, I hereunto subscribe my name this 26th day of April, A. D. 1916.

CHARLES L. GOODRUM.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

